Face masks find utility in a variety of medical, industrial and household applications by protecting the wearer from inhaling dust and other harmful airborne contaminates through their mouth or nose. The use of face masks is a recommended practice in the healthcare industry to help prevent the spread of disease. Face masks worn by healthcare providers help reduce infections in patients by filtering the air exhaled from the wearer thus reducing the number of harmful organisms or other contaminants released into the environment. Additionally, face masks protect the healthcare worker by filtering airborne contaminants and microorganisms from the inhaled air.
The section of the face mask that covers the nose and mouth is typically known as the body portion. The body portion of the mask may be comprised of several layers of material. At least one layer may be composed of a filtration material that prevents the passage of germs and other contaminants therethrough but allows for the passage of air so that the user may comfortably breathe. The porosity of the mask refers to how easily air is drawn through the mask. A more porous mask is easier to breathe through. The body portion may also contain multiple layers to provide additional functionality or attributes to the face mask. For example, many face masks include one or more layers of material on either side of the filtration media layer. Further components may be attached to the mask to provide additional functionality. A clear plastic face shield intended to protect the user's face from splashed fluid is one example.
When using a properly donned face mask, the heat and moisture of the user's exhaled breath tends to concentrate inside. As this humidified air escapes the face mask, it can condense on the user's eye wear or face shield causing fogging which may hamper the sight of the healthcare worker.
A method to eliminate fogging of eye wear or face shields resides in providing a seal across the upper edge of the face mask and the user's face to prevent moisture from escaping upwards. Aside from being uncomfortable, the seal on the face of the user is not always complete and moisture may be able to escape therethrough. Additionally, moisture may escape through the body portion of the face mask and subsequently condense on the eye wear or face shield.
Another attempt to reduce fogging has been made by providing an absorbent core between an inner and outer layer of the face mask. This approach may be problematic, for example, in that moisture may propagate along the inner surface of the inner layer of the face mask and exit therefrom so as to condense on the eye wear or face shield without contacting the absorbent core.